Photochromic compounds are those capable of reversible color change under the influence of electromagnetic radiation at certain wavelengths. For example, certain photochromic compounds may exhibit a different color when exposed to ultraviolet (UV) radiation or sunlight, and return to their initial colors when the such exposure ceases. Such returning to the initial color may be effected alternatively by thermal treatment and/or exposure to an electromagnetic radiation at a different wavelength.
Photochromic compounds find application in various fields, for example, for the manufacture of photochromic ophthalmic lenses, contact lenses, solar protection glasses, filters, camera optics or photographic apparatus optics or other optical devices and observation devices, glazing, decorative objects, bill elements or even for information storage by optical inscription (coding). The photochromic compounds, sometimes referred to as photochromic dyes, confer photochromic properties to these manufactured articles.
In the field of photochromic ophthalmic optics, and in particular the spectacle lens market, it is desired that a photochromic lens comprising one or more photochromic compounds has the following traits:    a high transmission in the absence of ultraviolet light;    a low transmission (high colorability) under solar irradiation;    acceptable coloration and discoloration kinetics;    a tint desired by the consumer (preferably grey or brown) with preferably a maintenance of the chosen tint during the coloration and discoloration of the lens;    maintenance of the performance and properties within a temperature range of 0-40° C.; and    a significant durability, as they are sophisticated and expensive products.
These characteristics are determined, inter alia, by the active photochromic compounds contained in the lens matrices, which must further be compatible with the matrices material, be it organic polymer or inorganic.
In addition, it is now understood that in order to obtain a desirable color of the photochromic ophthalmic lens, such as brown or grey, the use of a combination of at least two complementary photochromic dyes may be necessitated. Such complementary dyes exhibit different colors, viz., they have distinct maximal absorption wavelength in the visible range between 400-700 nm. This combination further imposes other technical requirements of the photochromic compounds. In particular, the coloration and discoloration kinetics of the (two or more) supplementary photochromic dyes may be advantageously essentially identical. The same applies for their stability over time and also for their compatibility with the plastic or inorganic support material.
Among the numerous photochromic compounds described in the art, benzopyrans and naphthopyrans have been documented, for example, in the following literature: U.S. Pat. Nos. 3,567,605; 3,627,690; 4,826,977; 5,200,226; 5,238,981; 5,411,679; 5,429,744; 5,451,344; 5,458,814; 5,651,923; 5,645,767; 5,698,141; WO-A-95 05382; FR-A-2,718,477; WO-A-96 14596; and WO-A-97 21698. Generally, the photochromic compounds have the following reduced formulae (F1), (F1′) and (F1″):
(F1)(F1′)(F1″)benzopyrans2H-naphthopyrans3H-naphthopyrans
U.S. Pat. No. 5,645,767 describes naphthopyrans (F2) having an indeno group linked to the 5- and 6-carbons of the 2H-naphthopyran skeleton:

U.S. Pat. No. 5,651,923 describes 2H-naphthopyrans (F3, F4) having a naphthofurano or benzo group linked to the 5- and 6-carbons of the 2H-naphthopyran skeleton:

U.S. Pat. No. 5,783,116 describes derivatives of 2H-naphthopyrans (F5, F6) having a non-substituted alicyclic group:

WO 01/36406 discloses 3H-naphthopyran derivatives (F7, F8) having a benzo 5- or 6-membered aliphatic ring linked to the 5- and 6-carbon of the 3H-naphthopyran skeleton:

U.S. Pat. No. 6,506,538 describes a group of photochromic 2H-naphthopyran compounds having the following general formula (F9) wherein the annelated ring (A) can be (F9-1), (F9-2), (F9-3), (F9-4) and (F9-5):
(F9)(F9-1)(F9-2)(F9-3)(F9-4)(F9-5)
These compounds were described in the above references to have photochromic properties. However, in reality, even though these compounds may have one or more of the desired properties described supra, such as a high transmission in the absence of ultraviolet and a high colorability under solar irradiation, few, if any, of the compounds described hitherto have the complete combination of the properties sought after which are necessary for the production of satisfactory articles. In particular, few, if any, of these compounds is intrinsically grey or brown. Therefore, the necessity of using an additional photochromic dye in order to obtain one of these two tints still exists.
In this context, it would be useful to be able to modify the photochromic compounds of each coloration such that final adjustment of the tint is permitted. Taking the formula (F9) supra as an example, where R1 or R2 is a phenyl, the presence of a donor group on the para position can lead to variable amount of bathochromic shift of the absorption band of the photochromic compounds. However, it has been found that the bathochromic shift obtained by substituting an alkoxy group with an amino group is too large (30-40 nm at minimum). Therefore there exists the necessity of obtaining an intermediate shift.
Japanese Patent Application Publication No. 2001-114775 describes compounds where the group R1 is a phenyl substituted on the para position by an amine substituted by electro-attracting groups such as sulphonyls or acetyls. An example compound as disclosed in this document has the following formula (F10):

The absorption wavelengths were therefore significantly lowered (−15 to −30 nm) relative to the comparative examples having morpholino groups. On the other hand, the discoloration kinetics of the compounds is significantly compromised as discovered by the present inventors, though this was not mentioned in this document.
The inventors of the present invention discovered a group of new compounds having a combination of the desired bathochromic shift in their absorption bands compared with analogous compounds having alkoxy, and, unexpectedly, advantageous photochromic properties, notably more rapid discoloration than those having sulphonyls or acetyls.